As a conventional magnetic position sensor, for example, there has been known that described in Japanese Patent Application Laid-Open No. H8-35809. The magnetic position sensor is constituted by a rotor provided with a cylindrical permanent magnet adhered to an inner wall surface of a cylindrical yoke (armature) fixed to a rotary shaft, two stators formed in a semicircular shape in an inner side of the rotor so as to be separated into two pieces, a Hall element arranged between these two stators, and the like.
Further, when the rotor rotates around the two stators, a magnetic flux flows, for example, according to a route in an order of the permanent magnet, one stator, the Hall element, another stator, the permanent magnet, the yoke(armature) and the permanent magnet. At this time, since the magnetic flux passing through the Hall element changes on the basis of a position of the rotor, a voltage corresponding to the change is output from the Hall element, whereby a rotation angle of the rotor is detected.
This axially symmetrical configuration prevents output fluctuation even if there occurs a displacement of the rotor.
However, in the conventional magnetic position sensor, a range in which a magnetic force changes is fixed to 180 degrees. Accordingly, when a range of detection is narrow, for example, 15 degrees, a value of the magnetic force change becomes small such as 15 degrees/180 degrees, so that since an angle of operation is detected by a little magnetic force change, an accuracy of detection becomes deteriorated. Further, it is impossible to detect at 180 degrees or more.